The present invention relates to a traction drive unit suitable for a rotating tool, such as a hand tool or a precision hole cutting machine adapted to cut laminated layers.
A conventional hand tool is such that power generated by a motor is decelerated via a gear type decelerator and transmitted to an output shaft to which a drill or the like is coupled. However, the conventional hand tools have the following default. Since the output shaft is directly coupled to the motor via the gear type decelerator, the motor can be abruptly stopped from rotating when excessive torque is applied to the output shaft.
In the case of a hand tool, the whole drill is vibrated so that an operator receives a shock and is in danger of the hand tool dropping.
In a conventional precision hole cutting machine, using a traction drive mechanism of a conventional planet type for laminated layers, the vibration of a motor is directly transmitted to a spindle via gears so that preciseness of the hole cutting is reduced. Further, in hole cutting a very thin film of metal, the metal foil may turn over and any precise hole cutting is therefore difficult.